Chemical process



Dec. l5, 1942. c. EQ HEMMlNGl-:R

i *if-.32. 2# messa/ y0) a STE AM OUTLET 4 `AS nu. INLIT 7 l Patented lee. 15,

Charles E. Hemmingen', Westfield, N. J., assigner l to Standard Oil Development Company, a corporationof Delaware Application December l, 1939, Serial No. 307,015

OFFICE The present invention relates to improvements in the conversion of relatively high boiling hydrocarbons yto fractions boiling Within the gasoj line range. More particularly, the'present invention relates to vapor phasecatalytic cracking of relatively high boiling hydrocarbons under con" ditions such that when the fresh feed is vaporized, at least a portion of the catalyst is present in the oil during the transition from `'theliquid to the vapor phase.

One object of the present invention is to crack hydrocarbons in the presence of a powdered catalyst suspended in the hydrocarbon vapors under conditions such that the tar or coke whichis formed during this type of operation, which tends to deposit on the inner wallsof -tubes or other surfacescontacting `the hydrocarbons during the-reaction, is removed from the said walls of tubes or surfaces or to prevent such deposition in the rst instance, by virtue of the scrubbing or abrasive action of the catalyst. Y

Another object of the present invention is tovaporize the entire fresh feed in the presence ofV catalyst -thus avoiding the -usual :dash towers.

To the accomplishment of the foregoing and similar, ends, I provldea process which is fully disclosed in the present speciiication and claims, reference being alsoV had drawing. v g

The `drawing is a diagrammatic illustration in partial vertical sectionA showing suitable apparatus in which my present invention may be carried into eifect. y

.to the accompanyingy of about 900A F. and containing the catalyst, is then discharged into line I0. At this point, the remainder, if any, of the catalyst is introduced into the vaporized oil through valved line Il into mixing device or injector l2. The vaporized oil containing the catalyst suspended therein is 'then discharged into line Il, thence into drum I5` where themain reaction takes place. The reaction products are withdrawn through line I6 and then discharged into a, cyclone separator Il` Where the majorportion of the catalyst is removed from the vapors. The separator Il may be of conventional design and'furthermore, two or more of 4these separators may be employed in series. The vapors are withdrawn from the separator through line I8 and discharged into frac- .tionating column I9, from which an overhead productcontaining gasoline and normally gaseous hydrocarbons are Withdrawn through line 20, discharged into. a condenser 2|, thence into a receiving drum 22 from which the normally gaseous hydrocarbons are withdrawn through line 23 and gasoline and the greater portion of the unconverted gas oil are recovered .through line 24.

Ihe bottoms fromtower I9 are withdrawn through line 25 and returned to line I6 as indicated. Thebottoms fromtower l0 will contain the remainder of the catalystwhich was not removed by the cyclone separator.

The cyclone separator il may be superimposed con bailied tower 30 and the catalyst liberated in Referring 1n detail to the drawing, a distillatel gas oil obtained either from crude petroleum oi-l or Vfromva cracked stock, is introduced into the 4 system through line l.' 'I'his gas oil may be the usual material understood by the term, e.. g. a product having a mid-boiling point of about 700. F. vA catalyst such as an acid treated clay or a silica gel, silica-alumina compositions or gels or the like is removed from some suitable reservoir 2, by any feeding means such as a star conveyor I and then forced through line l and line 5 into injector 8 where it admixes with the gas oil. The amount of catalyst introduced .fromfreservoi'r 2 s to line l may be from 10 to 100% of the total amount eventually introduced into the oil; Good resultsare obtained by introducing from about 10% to 25% o! the-total catalyst/aty this point.

The mixture of oil and catalyst, is Vthen dise` charged, into line, 'l Vand thence into a coil I in furnace 0 where the oil from the liquid to the vapor phase in the presence ofthe catalyst.

The vaporized'oil, having en outlet temperature separator I1 may fall through the tower against steam admitted through line 3|. The steam serves to purge the catalyst of volatile hydrocarbons. Nitrogen, CO2, flue gas or any heat stable gas not containing substantial quantities of free oxygen may also be used for this purpose. 'From tower 30, the catalyst is discharged through star feeder 34 into liIie 35 and thence into injector 36. Meanwhile a. heated regeneration gas is fed from line 31 into injector 3l where it disperses the catalyst causing entrainment orsus- Dension of the latter in the gas and this mixture is withdrawn through line 38, and forced into a coil 38 in'heat exchanger 40 where tarry deposits l0r coke on the catalyst are burned oil. Good re,-

`cults are" obtained in the regeneration a regeneration gas'containing 2% to 10% oxygen.

the remainder being Na. steam, CO2, ilue gas or or back pressure indischarge line 4l 'of say 1 to 4 atmospheres onthe pressure gauge.- Sonie o! KIA v heat developed in coil I9 may be withdrawn by forcing water, admitted through line 43 into heat exchanger, through the bank of pipes forming coil 38, but externally of the several pipes. The

-steam formed may be withdrawn through line 44. Molten salt may also be used in place of ess may be made without departing from the.

spirit of the present invention. For instance, the gas oil distillate may be heated in coil 8 to a temperature from about 300 to 600 F., at preseures from the range of 10 to 50 pounds or from vtemperatures as high as 800 F. where the pressures are greater than 100 pounds per square inch gauge. The temperature of the material leaving coil 8 may be as high as 1000 F. The catalyst which is in powdered form may have a size varying in the range from about 100 to 400 mesh. The temperatures prevailing in the cracking vessel Il may vary from 750 to 1000 F. The

ascaooa so that the residual heatv from regeneration may` be used to heat the oil or its vapors.- The vapors may be resident in the cracking vessel I for a time within the range of from about 5 to 25 seconds. Furthermore, the drum i5 may be merely aninsulateddrum oritmaybe aheated drum or coil. Y

Numerous modications of my invention may be made by those skilled in this art and itis my intention to claim the invention as broadly as the language of the appended claims will permit.

What I claim is:

l. In a process for the catalytic cracking of hydrocarbon oil in the presence of a nely divided regenerable catalyst which remains solid under the cracking and regenerating conditions, the improvements which comprise adding to the oil while it is in liquid condition a portion of the totalquantity of cracking catalyst which is to be used, vaporizing the oil in the'presenee of said portion of the catalyst, then adding to the vaporized oil the remainder of the catalyst prior to any substantial cracking of said oil vapors and thereafter maintaining said oil in contact with said catalyst for a period suilicient to obtain substantial cracking thereof. 2. Process according to claim 1 in which a minor proportion of the total quantity of cracking catalyst to be used is added to the oil while it is in liquid condition.

pressures in this element may'vary from atmos-V pheric to 500 pounds per square inch gauge.

Steam or other vapors may be added to the feed to coil 8 to assist in the vaporization of the oil therein. The total catalyst to oil ratio may vary from5to20partscatalystper1partoilby weight. The catalyst may be hotter than the oil 3. Process according to claim l in which from 10 to 25% of thel total quantity of catalyst is added tothe oil while the latter is in liquid condition.y

fi. Process according to claim 1 in which hot freshly regenerated catalyst is added to the oil both before and after vaporizatlon. l 

